Illegal immigrants wait in line to get passports outside the Mexican Consulate in Houston in August, after the Department of Homeland Security began accepting applications to allow them to avoid deportation. (AP)

Two law professors, including one who served in the Bush Justice Department, have published a paper charging that President Obama violated the Constitution with his directive to law enforcement not to deport illegal aliens.

In the paper entitled, “The Obama Administration, the Dream Act and the Take Care Clause,” authors Robert Delahunty of the University of St. Thomas [Minnesota] and John Yoo, a law professor at University of California at Berkeley and former U.S. deputy assistant attorney general, blast Obama's moratorium on deporting certain illegal immigrants. The professors dismissed the idea that the decision on whether to deport illegal immigrants who are arrested for minor infractions is a matter of prosecutorial discretion.

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“If there’s one case and it’s left to the prosecutor, well that’s fine, but what Obama did was take a million cases and leave it up to prosecutorial discretion," John Yoo told FoxNews.com. “The only reason it’s under [Department of Homeland Security Secretary] Janet Napolitano’s discretion is because Obama had made his decision. If she’s doing it under her own, she would have to be fired.”

An abstract for the paper debunks the claim that the president has the Constitutional authority to not enforce civil laws crafted and passed by Congress.

“It’s the duty of the president. He must always uphold the law,” Yoo said, adding that the only exceptions in doing so are if laws are unconstitutional or if prosecuting them can be reasonably deemed not viable.

Officials from the White House declined to comment on the paper, referring FoxNews.com to DHS.

“The authority of the Secretary of Homeland Security to exercise prosecutorial discretion, including by granting deferred action, has long been established and has been recognized by the Supreme Court," said DHS spokesman Peter Boogaard. "This authority was reaffirmed by the Supreme Court just this year [Arizona v. United States (2012)].”

“That said, DHS’s deferred action for childhood arrivals process is only a temporary measure that does not provide a path to citizenship; Congress must still act to provide a permanent solution to fix the broken immigration system. Until Congress acts, DHS is dedicated to implementing smart, effective reforms to the immigration system that allow it to focus its resources on common sense enforcement priorities, including criminals and other public safety threats."

In June, President Obama announced that the deporting of young, undocumented immigrants who match criteria from already-proposed DREAM Act lesgilastion would end under his administration’s watch. The effect was to put in place most of the measures in the act, but by administrative order, not through the legislative process. In August, a group of federal agents filed a lawsuit against DHS secretary Janet Napolitano, claiming that the new directive forces them to break the law.

Under the DREAM Act, illegal aliens who are eligible beneficiaries would not have faced deportation as long as they meet the following criteria:

Proof of having arrived in the United States before age 16.

Proof of residence in the United States for at least five consecutive years since their arrival date.

Register with the Selective Service if they are male.

Be between the ages of 12 and 35 at the time that the bill was enacted.

Obtained a high school diploma of GED, or admitted to an institution of higher education.

Be of good moral character.

Opponents of the DREAM Act, which still has not been passed in Congress, say that it - as well as Obama's order, encourages illegal immigration while adding economic and social burdens to the United States.

Sen. Marco Rubio (R-Fla.), who was a key backer of the DREAM Act, blasted the president's preemption of the in June, when DHS announced policies on immigration enforcement that.

“There is broad support for the idea that we should figure out a way to help kids who are undocumented through no fault of their own, but there is also broad consensus that it should be done in a way that does not encourage illegal immigration in the future. This is a difficult balance to strike, one that this new policy, imposed by executive order, will make harder to achieve in the long run.”

“…by once again ignoring the Constitution and going around Congress, this short term policy will make it harder to find a balanced and responsible long term one.”

Perry Chiaramonte is a reporter for FoxNews.com. Follow him on Twitter at @perrych